1. Technical Field
The present invention relates to a lighting device using a light guide. The invention is also concerned with a liquid crystal display unit using the above type of lighting device. The invention further pertains to electronic equipment using the above type of liquid crystal display unit.
2. Discussion
Liquid crystal display units are being widely used as visible information displays for various types of electronic equipment, such as mobile cellular telephones, video cameras, etc. In this type of liquid crystal display unit, the orientations of liquid crystals are controlled to modulate light, thereby displaying characters, numbers, and other visible information. The liquid crystal display unit is generally formed in the following manner. A driver IC is attached to a liquid crystal panel so as to form a liquid crystal module. Further, a lighting device and a reflector are fixed to the liquid crystal module.
Hitherto, as the foregoing lighting device, the lighting device shown in FIG. 10 is known which has a planar light guide 101 and point-source lights 102 which are positioned to face a light incident surface 101a of the light guide 101. In this conventional device, the light emitted from the point-source lights 102 is diverged by lenses 103, respectively, and the diverged light then radiates in a planar form from a light emitting surface 101b of the light guide 101.
In the above known type of lighting device, however, the area in which the light emitted from the point-source lights 102 can be guided is restricted to predetermined angular areas A. A sufficient luminance level of light can be obtained in the areas A, but not in the portions outside the areas A. As a result, the overall light emitting surface 101b cannot emit light with a uniform luminance level.
In view of the above problem, it is an object of the present invention to provide a lighting device in which the light having a uniform luminance level can emit from the overall planar light emitting surface of a light guide when the light is applied to the light guide from point-source lights.